^thats actually illegal...in order for any car warranty to be voided, the change made must be directly related to the failure...say if your fuel pump goes they can't void the repair...if the cat goes bad they would probably be able to void it although it is unrelated
If you are really worried, you can pay the premium for the BMW performance exhaust
2007 //M Coupe. BSM. Fabspeed headers. Catless. BMS x-pipe. Strömung cans. evolve tune. Fortune/Broadway Static 500 coilovers.